1. Field of the Invention
The present invention relates generally to the field of welding chill rings for joining adjacent lengths of metallic pipe, and more particularly, is directed to novel partially consumable spacer chill rings and a method for welding pipe joints therewith.
2. Description of the Prior Art
In the welding industry, it is presently the usual practice to employ a chill ring at each pipe joint to facilitate the introduction of filler metal from a separate source during the first root pass. Spacer pins are usually employed in conjunction with the chill ring to precisely set the distance between adjacent pipe ends for better control and reliability in the pipe joining operations. In one known process, a gas is introduced interiorly of the pipe during the welding procedures and upon completion of the joint; the pipe must be purged by employing auxiliary equipment.
The existing methods of pipe welding and most existing chill rings which are currently available to aid in the fabrication of pipe joints frequently result in defective welds which can be caused by such hard to control imperfections as burn through, the formation of icicles and slag interiorly of the pipe, or in porosity in the weld itself. Additionally, most prior techniques involved manual welding procedures, which are always subject to human error, during welding of the first root pass due to the wide variance possible in the welder's flow of filler metal.
In an effort to reduce the number of defective joints resulting from the use of prior chill rings and manual welding techniques, other prior workers in the art have developed "ridge" type machined chill rings to bring greater reliability to the welded pipe joint, and to reduce costs by diminishing the number of rejects. However, the costs of producing the "ridge" type machined ring itself contributed to the increased overall cost of the finished welded pipe junction. Presently available pipe joining welding products or chill rings, are used to assist in aligning the pipe ends, together with a spacer pin or pins, to create a root gap for initiation of the welded joint, for which the separate introduction of filler metal during the first root pass is essential.
Presently available chill rings are in general use to provide spacing pins or nubs for root gap spacing purposes in various welding processes. A root gap of perhaps 3/16 of an inch or 1/18 of an inch was previously set by the pins and then filler metal was added during the first root pass. When the welding element, stick, rod or wire was consumed, manual operations had to be discontinued and then restarted after a new stick was employed or the welder's position changed. This was a time consuming, manual process with the inherent possibility of a defect occurring in the weld, due both to the manual operations and to the intermittent nature of the weld.
Although current available products can provide the required alignment and root gap spacing functions, none eliminate the need for separate addition of filler metal.
It is apparent from the foregoing that a need remains in the art for improved chill rings which facilitate and simplify the welding operation.
It is a primary object of the present invention, therefore, to provide improved chill rings which reduce or eliminate defective welds caused by burn through, the formation of icicles and slag outside the pipe, or porosity in the weld.
It is another object of the invention to provide improved chill rings which may be used with automatic welding heads and thus, prevent defective welds due to human error.
It is still another object of the invention to obviate the need to employ expensive machined "ridge" type chill rings.
It is another object of the present invention to provide an improved partially consumable spacer chill ring which will provide filler metal during the welding operation and thus reduce both the incidence of defective welds and welding time.
It is another object of the present invention to provide a novel partially consumable spacer chill ring including a non-consumable cylindrical base metal chill ring and an annular consumable filler metal spacer ring affixed to the outer periphery of the base metal ring; the latter providing filler metal during welding.
It is another object of the present invention to provide a novel partially consumable spacer chill or welding ring comprising a cylindrical base metal chill ring and a consumable spacer ring affixed to the outer periphery of the base metal ring at a plurality of circularly offset locations.
It is another object of the present invention to provide a novel partially consumable spacer chill ring that is simple in design, inexpensive in manufacture, and trouble-free when in use.
It is still another object of the invention to provide a novel partially consumable spacer chill ring including a cylindrical base metal chill ring having an annular alignment groove around the outer periphery thereof, and an annular consumable filler metal spacer ring fitted on said annular alignment groove of the base ring.
It is another object of the present invention to provide a novel, partially consumable spacer chill ring comprising a non-consumable cylindrical base metal ring having its inner land provided with upstream and downstream bevels and having a consumable circular ring affixed about the chill ring outer land and wherein the chill ring and the spacer ring are provided with aligned splits.
It is another object of the present invention to provide a novel, partially consumable spacer chill ring comprising a non-consumable cylindrical base ring, an annular consumable spacer ring affixed to the outer periphery of the base ring and wherein either or both of the base ring and the spacer ring may be split.
It is another object of the present invention to provide a novel method of welding a pipe joint which requires no spacer pins and employs no purging gases or purging dams.
It is another object of the present invention to provide a novel, partially consumable spacer chill ring which eliminates the necessity of employing filler metal during the first root pass, whereby a completed weld may be produced in a single pass.